Stress incontinence is a very common condition that involves losing urine unintentionally during physical activity such as exercise, coughing, sneezing or laughing. It is women primarily that experience stress incontinence, often as a result of weaknesses that have been caused in bladder-supporting muscles during childbirth, or as a result of menopause, injury, surgery, or obesity. Despite being very common, women who suffer from stress incontinence or excess fluid release often feel ashamed or embarrassed to be seen wearing or buying the bulky disposable products available in the market.
In the female urinary system, the bladder stores urine produced by kidneys, and is contracted to push out the urine when it is convenient and socially acceptable to do so. There is a sphincter muscle surrounding the bladder neck at the bladder exit, where the bladder neck connects to urethra for conveying the urine outside of the body. The urethra extends from the bladder neck to an outlet located near the cervix in the vagina.
The condition of the pelvic floor muscles, located at the base of the pelvis, has much to do with urinary incontinence. The pelvic organs (the bladder, the vagina, the uterus and the rectum) are supported by a complex “hammock” that includes different types of muscles and tissues. The pelvic floor muscles help to support the sphincter muscle that keeps the bladder closed while it fills with urine.
The female urethra is composed of four (4) separate tissue layers that keep it closed. The inner mucosal lining keeps the urothelium moist and the urethra supple. The vascular spongy coat produces the mucus important in the mucosal seal mechanism. Compression from the middle muscular coat helps to maintain the resting urethral closure mechanism. The outer seromuscular layer augments the closure pressure provided by the muscular layer.
Fast-twitch fibers in these muscles cause the sudden stopping of the urinary stream to provide the voluntary guarding reflex. With acute increases in intra-abdominal pressure, forceful contraction of the fast-twitch levator fibers elevates the pelvic floor and tightens intact connective tissue planes, thereby supporting the pelvic viscera.
Deficiency in the hammocklike support of the endopelvic connective tissue, coupled with relative preservation of the preferentially anterior urethral support of the pubourethral ligaments, may partially explain the complex rotational and descending motion of the bladder neck commonly observed in association with stress incontinence. The pubourethral ligaments may serve to limit downward motion of the anterior urethral wall and provide a pivot point for rotatory motion around the pubic bone. Some theorize that this preferential anterior wall support also may serve to pull the anterior and posterior urethral walls apart during straining, thereby contributing to bladder neck incompetency and stress incontinence.
Unlike in males, where the bladder neck and the prostate comprise the internal urinary sphincter, the internal sphincter in females is functional rather than anatomic. The bladder neck and proximal urethra constitute the female internal sphincter. The female external sphincter (i.e., the rhabdosphincter) has the most prominent effect on the female urethra at the urogenital triangle. Located approximately 1.8 cm distal to the bladder neck, it exerts influence for a distance of approximately 1.5 cm of urethral length.
The female urethra contains an internal sphincter and an external sphincter. The internal sphincter is more of a functional concept than a distinct anatomic entity. The external sphincter is the muscle that is known to be strengthened by Kegel exercises.
While there are numerous physical/muscular conditions that can interfere with the normal functioning of the bladder and the sphincter leading to incontinence, there can be neurological causes also. For example, signals sent from the bladder to the brain may be interfered with due to nerve damage caused by diseases such as diabetes, Parkinson's disease, multiple sclerosis, or strokes due to high blood pressure, leading to incontinence resulting from signal miscommunications.
Products are known for dealing with leakages such as menstruation. However, there are differences between the physical attributes of such leakages and those of stress incontinence, including fluid pressure and volume per emission. Furthermore, the placement of the urethra is further forward in the vagina than where menstruation fluids are excreted. Involuntarily leakages during stress incontinence come from the urethra which is composed of 4 different tissue layers that keep it closed. Fast-twitch fibres in these muscles cause the sudden stopping of the urinary stream to provide the voluntary guarding reflex. It is the weakening of these muscles that causes stress incontinence. However, the muscles often retain some retracting capabilities, and this prohibits women from excreting the full contents in their bladder.
It has been observed that, when urine is released from the urethra as the result of stress incontinence, it is released in spurts directed generally at the same position and angle each time. A stress incontinence product is required to perform differently than a general “leakage product” i.e. more specifically, it is required to perform differently than a product designed solely for menstruation. Furthermore, women often prefer garments that will contact their skin with natural fibres, such as cotton.
Various absorbent articles and protective garments are known. For example, U.S. Pat. Nos. 5,677,028 and 5,879,487 to Ravella each disclose an absorbent material and method for making same comprising a fibre web, including a fibre blend comprising from about 50 to about 75 weight percent of a fibre having fineness less than about 3 denier and from about 25 to about 50 weight percent of a fibre having fineness ranging from about 3 to about 5 denier wherein the fibre web is bound together by fibre bundles transverse to the plane of the web. The fibre blend may further comprise from about 3 to about 7 percent by weight of a fibre having fineness greater than about 5 denier. The fibres comprising the fibre blend may be entirely hydrophobic, or the about 3 to about 5 denier fibre may be hydrophilic. The absorbent material exhibits a high degree of absorption and fluid retention and does not wet back even under compression. The transverse fibre bundles formed during the mechanical bonding of the web function as wicks for transferring fluid from the surface of the material to the inner portion of the material. The fibre bundles also act as support structures resisting compression and maintaining void space and absorbent surface area within the material, even when wet. The material is reusable and is strong enough to withstand numerous washings. The material is useful as a component of reusable absorbent products further comprising an outer layer or body-side layer. The outer layer may be fluid impermeable, gas permeable or both.
Canadian Patent Application No. 2,152,135 to Ravella discloses a breathable absorbent pad having a fluid impermeable and gas permeable bottom layer and a moisture absorbent layer disposed on said bottom layer. In an embodiment, the absorbent pad may further comprise a fluid permeable top layer wherein the absorbent material is disposed between the top layer and the bottom layer. According to the patent application, high density stitching unexpectedly improves the absorbency of a graduated density non-woven material usable as the moisture absorbent layer with or without the top layer. The application also discloses a method of making a breathable absorbent pad comprising the steps of providing a fluid impermeable and gas permeable bottom layer, a moisture absorbent layer and securing the layers together. Stitching of the top and bottom of a binding material through the layers secures the layers together. The method may further comprise the step of providing a top layer and stitching the top layer and the moisture absorbent layer together.
U.S. Pat. No. 6,381,994 to Lee discloses a method for making a woven or knitted fabric with water transition ability, involving the steps of fabricating a woven or knitted fabric having a double weave structure by use of a polyethyleneterephthalate (PET) filament for one surface of said fabric and a divided PET/nylon-conjugated fibre for the other surface of said fabric, and subjecting said fabric to a weight loss finishing process. According to the patent, since the fabric has a void size difference between the surfaces thereof in accordance with the weight loss finishing process, it can externally discharge, at a high velocity, moisture absorbed therein.
U.S. Pat. No. 8,117,675 to Strange et al. discloses a waterproof panty with rolled over welded seams. According to the patent, the rolled over welded seam will inhibit the leaking of bodily fluids at the leg openings caused by stitching and wicking. The panty has an outer shell and an inner panty layer. The outer shell a continuous cut formed of a soft blend laminated fabric. It is liquid proof, breathable, hypo-allergenic, stain resistant, and elastic. It is cut to form a waist opening and two leg openings. If desired stretchable lace or elastic side portions can be provided. The inner panty lining is a breathable soft blend fabric and includes a front portion, back portion and a crotch portion. The crotch portion is double layered for added dryness. The inner panty layer is cut to the full design of the panty having a waist opening and two leg openings.
U.S. Pat. No. 6,610,901 to McMahon-Ayerst et al. discloses a protective garment, which may be in the form of an undergarment or outerwear, such as a swimwear. The garment includes a body conforming portion for preventing leakage of body waste liquids. The garment includes, at least in the area of the garment which might come into contact with the body waste liquids, sheet material which comprises a lamination consisting of only two laminae. The first lamina is a liquid permeable fabric and the second lamina is a liquid impermeable but vapor permeable material. The liquid permeable fabric is positioned interiorly of the liquid impermeable but vapor permeable material having regard to the inside and outside of such a garment. Liquids are permitted to pass into and through the inner liquid permeable lamina to the interface between the inner laminae and liquid impermeable outer laminae whereat this liquid can be evaporated or dehydrated through the vapor permeable outer laminae.
U.S. Pat. No. 7,951,128 to Lewis discloses a protective undergarment system for absorbing fluids released by the body of a user. The protective undergarment system includes an upper member being designed for being selectively positioned around an abdomen, a groin and a posterior of the user. The upper member comprises a lower aperture extending through the upper member whereby the lower aperture is designed for extending from a portion of the groin to a portion of the posterior and passes between the legs of the user. A lower member is selectively coupled to the upper member whereby the lower member is selectively positioned over the lower aperture of the upper member to selectively close the lower aperture of the upper member. The lower member is designed for absorbing the fluids released by the body whereby the lower member can be removed from the lower member when the lower member is soiled.
U.S. Pat. No. 6,861,520 to Todd et al. discloses a process for chemically bonding an odor-encapsulating agent to textiles includes reacting a cyclodextrin with a cross-linking agent capable of forming ether bonds with the cyclodextrin and with the textile material, and curing the textile material treated with a mixture of the cyclodextrin and cross-linking agent. Preferably, the cross-linking agent is imidazolidone, which forms an ether bond with a hydroxyl group on the cyclodextrin and with a hydroxyl group. In textile materials containing cellulose, imidazolidone forms an ether bond with a hydroxyl group on the cellulose. An active agent can be complexed with the cyclodextrin for release. Textiles formed by such a process can comprise an article of clothing adapted to trap odors emanating from a wearer.
U.S. Patent Application Publication No. 2010/0249736 to PNG et al. discloses protective garments comprising an inner surface or portion of an inner surface with both absorbent and stain resistant properties while maintaining the soft feel, breathability and aesthetic properties associated with traditional “non protective” intimate apparel. The fabrics and methods of constructing the garments are also disclosed.
Korean Patent Registration No. 10-0694187 to Lee discloses an absorbent pad including a water preserving layer having functions of absorbing and storing moisture, a waterproof layer for preventing permeation of the moisture, and a water repellent treatment portion formed along an edge portion of the water preserving layer. The absorbent pad is provided to prevent excessive absorbed urine or moisture from being penetrated into side portions of the pad by only storing the user's urine or moisture on the center portion of an absorbing layer. This is provided to prevent cloth from being wet due to leakage of water thereby providing sanitary and clean environment.
U.S. Pat. No. 7,008,887 to Rearick et al. discloses cellulosic substrates with reduced absorbent capacity having the capability to wick liquids, as well as to methods of manufacturing such cellulosic substrates. The cellulosic substrates provided comprise an inside and an outside connected to the inside. The inside comprises cellulosic fibres and has a reduced absorbent capacity, and the outside comprises cellulosic fibres. The outside may have a reduced absorbent capacity and may have an absorbent capacity higher than the inside. The cellulosic substrate is capable of wicking liquid contacting the inside of the substrate to the outside of the substrate.
While various combinations of materials and layers for absorbent articles are known, improvements are desirable for providing a highly-functional absorbent product suitable for dealing with stress incontinence while also being discrete, comfortable and desirable to wear.